1. Field of the Invention
The present invention relates to an engine speed control system for carrying out foot accelerator control in which an engine speed that corresponds to an output of the pedal sensor for detecting the operative position of the accelerator pedal is used as a target rotational speed.
2. Description of the Related Art
A work vehicle in which engine speed control is used is disclosed in Japanese Laid-open Patent Publication No. 1-195933, wherein an engine speed that corresponds to the output of the pedal sensor is used as the target rotational speed. This work vehicle is provided with an accelerator lever and a lever sensor for detecting the operative position the accelerator lever, the output rotational speed of the engine is controlled so that the engine speed that corresponds to the output of the lever sensor is obtained as the output rotational speed of the engine, and a constant speed control that holds the engine speed set based on the accelerator lever is achieved. The output rotational speed of the engine is controlled so that the engine speed stored in storage means is obtained as the output rotational speed of the engine on the basis of the on-operation of a switch, and a constant speed that corresponds to the engine speed stored in the storage means is maintained. In accordance with such a configuration, the degree of slippage can be reduced to increase the gripping force, and it is possible to easily escape from the slippage state by reducing the engine speed through operation of the accelerator lever when slippage occurs while the vehicle body is being made to travel in a constant speed state set by the accelerator level. However, after escaping from the slippage state, the accelerator lever must be operated so that the operative position of the accelerator lever is the same as the operative position prior to slippage in order to allow the vehicle body to travel in the same constant speed state as prior to slippage. Also, when slippage occurs while the vehicle body is being made to travel in a switch-induced constant speed state, the engine speed must be reduced by operation of the accelerator lever after the operation for cancelling the constant speed state has been carried out in order to escape from the slippage state.
In a conventional engine speed control such as that described above, there is a problem in that an escape from a slippage state or a return to a constant speed state following escape from a slippage state is not smoothly carried out when slippage occurs while the vehicle body is traveling in a constant speed state.